Hey there,
So I’ve checked the card effects of all Flower Cardian monsters. There is only 2 Flower Cardian cards that ignores Summoning conditions and they are “Flower Cardian Moonflowerviewing” and “Super All In!”:
Once per turn, during your Main Phase: You can draw 1 card, and if you do, show it, then, if it is a "Flower Cardian" monster, you can Special Summon it, ignoring its Summoning conditions, and it can attack directly this turn. If you activated this effect, skip the Draw Phase of your next turn. When this card is used as Synchro Material, you can treat it and all other Synchro Materials (that have a Level) as Level 2 monsters.
https://yugipedia.com/wiki/Super_All_In!
The other cards you stated have this in the following text:
If this card is Special Summoned: Draw 1 card, and if you do, show it, then you can Special Summon it if it is a "Flower Cardian" monster.
There is no bug. It’s working exactly as intended. Even if you draw a Flower Cardian with any of the above 4 monsters, you cannot ignore Summoning Conditions.